The present invention relates to an output control system for an interpolation dot pattern used in a word processor or a character generator which processes character font data in a dot matrix form.
In order to expand or contract a character or letter font of a defined dot matrix form in an apparatus such as a word processor for processing the character font, the number of original character pattern dots SD are simply increased or decreased, as shown in FIGS. 1A through 1C in accordance with a conventional simple expansion/condensation method.
A conventional expansion/condensation means of this type can be easily implemented at low cost. However, steps (i.e., narrowed portions) maybe visible at an inclined portion of a character when using this technique. Therefore, an output pattern may be different from the original character pattern and difficult to recognize, resulting in an unnatural character presentation and hence inconvenience.
The conventional dot interpolating means described above cannot easily create a modified type face such that an original character pattern or a character pattern with any magnification/condensation coefficient is inclined or rotated. In addition, even if the modification range is greatly limited, a distortion occurs in the modified character pattern. Conversion precision is greatly degraded and pattern conversion cannot be accurately performed.
The width or height or both of a modified character such as a rotated character or an inclined character is not expressed in a dot form in units of bytes. A scanning start position of a new character pattern created by dot interpolation does not match with a byte boundary of an image memory for writing image data in units of bytes when the new character pattern data is transferred from the dot interpolating means to the image memory. The image data cannot, therefore, be processed in further units of characters, resulting in inconvenience. According to a conventional dot interpolation technique, since the dot-interpolated character image is expanded with respect to a fixed position corresponding to scanning, an agate or a contracted character (having a width half of that of an em) cannot be vertically shifted by a few dots, resulting in inconvenience.
The width or height or both of a modified character such as a rotated or inclined character obtained by dot interpolation varies in accordance with a designated magnification or condensation coefficient and a rotation angle. In the worst case, a converted one-character dot image representing an expanded, rotated or inclined character cannot be stored in a one-line image area (e.g., an image line buffer). When a conventional character generating means is used, part of the character is omitted, and a single character is separated into portions printed on two different lines. Due to a functional problem, the conventional interpolating means cannot produce an image having a slice which is formed by multiple printing.
A width of the modified character such as a rotated or inclined character along the main scanning direction varies in accordance with a rotation angle and a magnification/contraction coefficient. For this reason, an underline or a side line corresponding to the character width must be drawn for each modified character.
A character pitch or a line pitch cannot be optimally kept in the modified character due to the problem described above.